Use Null Coalescing Operator

Do

public Book GetTheBestBook(Book book) { 
  return book ?? new Book () { Name = "C# in Depth" }; 
}

Don't

public Book GetTheBestBook(Book book) { 
  if (book != null) { 
    return book; 
  } 
  else { 
    return new Book() { Name = "C# in Depth" }; 
  } 
}